ELECTRICAL PROPERTIES OF THE HEART Flashcards
The 3 principal components that make up the cardiovascular system are:
- Heart (the pump)
- Blood vessels (the pipes)
- Blood (fluid to be moved)
4 Electrical Properties
- Excitability
- Automaticity
- Rhythmicity
- Conductivity
Property of readily responding to a stimulus
Excitability
Property of specialized excitable tissue that allows self-activation through spontaneous development of an action potential
Automaticity
Recurrence of cardiac contraction at regular and repetitive intervals
Rhythmicity
Ability to transmit electric impulse
Conductivity
Mechanical Property
Contractility: ability to contract and relax
[TRUE/FALSE]
The structure of the heart completely encircles the blood-filled chambers.
TRUE
[TRUE/FALSE]
The blood being pumped through the heart chambers does exchange nutrients and metabolic end products with the myocardial cells.
FALSE
Has only a limited ability to replace its muscle cells
Cardiac cells
Recent experiments suggest that only ___% of heart muscles are replaced per year
1%
[TRUE/FALSE]
Heart attacks that result in myocyte death are so hard to fix.
TRUE
Upper chambers of the heart act as a reservoir and a booster pump for venous return
Atrium
A weak primer pump for the ventricle
Atrium
Receives oxygenated blood from the pulmonary veins
Left atrium
Receives deoxygenated blood from the superior and inferior vena cava
Right atrium
Lower chambers of the heart receives blood from the atria
Ventricle
Maintains circulation of blood in the lungs and provides energy to propel blood in the pulmonary circulation
Right ventricle
Maintains circulation of the blood to other organs, provides energy to propel blood through the systemic circulation
Left ventricle
Whatever happens in the blood flow in the right ventricle will affect the blood flow in the left ventricle
Series
Propels blood through the lungs for exchange of O2 and CO2
Pulmonary circuit
Blood flow in one area will not affect the blood flow in other area
Parallel
Propels blood to the other tissues
Systemic Circuit
[Systemic/Pulmonary Circuit]
Serves many organs
Systemic Circuit
[Systemic/Pulmonary Circuit]
Multiple functions
Systemic Circuit
[Systemic/Pulmonary Circuit]
Regulate more complex
Systemic Circuit
[Systemic/Pulmonary Circuit]
Serves lungs only
Pulmonary Circuit
[Systemic/Pulmonary Circuit]
Single function
Pulmonary Circuit
[Systemic/Pulmonary Circuit]
Little control
Pulmonary Circuit
[Systemic/Pulmonary Circuit]
Larger volume
Systemic Circuit
[Systemic/Pulmonary Circuit]
High pressure area
Systemic Circuit
[Systemic/Pulmonary Circuit]
High vascular resistance
Systemic Circuit
[Systemic/Pulmonary Circuit]
Smaller volume
Pulmonary Circuit
[Systemic/Pulmonary Circuit]
Low pressure area
Pulmonary Circuit
[Systemic/Pulmonary Circuit]
Low vascular resistance
Pulmonary Circuit
Structures within the heart that open and close with the heartbeat to regulate the one-way flow of blood.
Heart Valves
Blood flow should be silent as long as it is smoothly flowing. If it hits anything that obstructs it, it will become turbulent and generate sound that can be heard with a stethoscope.
Abnormal Heart Sounds
Most causes of heart murmurs in adults are valve problems.
Abnormal Heart Sounds
Flap of a valve that may thicken, stiffen, or fuse together.
Stenotic or incompetent valves
[TRUE/FALSE]
The heart receives its blood supply via arteries that branch from the aorta behind aortic valve cups.
TRUE
The arteries that supply the myocardium
Coronary arteries
The blood flowing through the coronary arteries
Coronary blood flow
Most of the cardiac veins drain into a single large vein called __________ ______, which empties into the right atrium.
Coronary sinus
Changes in one or more of the coronary arteries cause insufficient blood flow to the heart (ischemia)
Coronary Artery Disease
Can lead to myocardial infarction or heart attack
Coronary Artery Disease
Include prolonged chest pain radiating to the left arm, nausea, vomiting, sweating, weakness, and shortness of breath.
Coronary Artery Disease Symptoms
Coronary Artery Disease Diagnosis is by:
ECG and cardiac markers
Occurs when blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle.
Myocardial infarction
Risk Factors for Atherosclerosis
- Cigarette smoking
- High cholesterol & amino acids in the blood
- Hypertension
- Diabetes
- Obesity
- Sedentary lifestyle
- Stress
Benefits of Exercise Against Heart Attack
- Decreased myocardial O2 demand
- Increased diameter of coronary arteries
- Decreased severity of hypertension & diabetes
- Decreased tendency of blood to clot
- Better control of blood glucose
Treatments and Interventions (astherosclerosis)
Drugs:
1. Nitroglycerin
2. Beta-blockers
3. Anti-coagulants
4. Statin
Intervention:
1. Cardiac catheterization
2. Coronary bypass
- Rapid depolarization
- Due to Na+ influx
Phase 0: Slow Depolarization
- Brief period of repolarization
- Due to K+ efflux and decrease in Na+ influx
Phase 1: Initial Repolarization
- Plateau of AP
- Due to increase in Ca2+ and decrease in Na+ influx
- Ensure adequate ventricular filling
Phase 2: Plateau
- Repolarization
- Decrease in Ca2+ influx and increase in K+ efflux
Phase 3: Repolarization
- Resting membrane potential (RMP)
Phase 4: Spontaneous Depolarization
The pacemaker of the heart
Sinoatrial Node (SA)
Has 0.1s delay to allow the atria to contract and to be filled
Atrioventricular Node (AV)
[Atrial/Ventricular Excitation]
- SA Node gives out impulse (Begins)
- AV Node/Atriums contracts (End)
Atrial Excitation
[Atrial/Ventricular Excitation]
- Atrial relaxes; branches of AV receive impulses
- Ventricle contracts = QRS complex
Ventricular Excitation
Latent or secondary pacemakers
Ectopic foci
Result of atrial depolarization
P-wave
Ventricular depolarization
QRS complex
Obscured by QRS complex
Atrial repolarization
Amount of blood pumped out of each ventricle
Cardiac output
What is the normal cardiac output?
5.25 L/min.
Difference between the End Diastolic Volume (EDV) and End Systolic Volume (ESV)
Stroke Volume
Positive chronotropic factors
High heart rate
Negative chronotropic factors
Lower heart rate
Ventricular repolarization
T-wave
Conduction through the AV node and AV bundle
P-R segment
A graphical record of the heart’s electrical activity
Electrocardiogram
- Inactivate fast-sodium channels
- Reduce the rate of depolarization (decrease the slope of phase 0)
Sodium-channel blockers (quinidine)
- Affect the plateau phase (phase 2) of the action potential
Calcium-channel blockers (verapamil and diltiazem)
- Delay repolarization (phase 3) by blocking the potassium channels
Potassium-channel blockers
Uncoordinated atrial and ventricular contractions caused by a defect in the conduction system
Arrhythmias
A rapid and irregular (usually out of phase) contraction where the SA node is no longer controlling heart rate
Fibrillation
Can cause clotting and inefficient filling of the ventricles
Atrial fibrillation
- When the ventricles pump without filling
- Major cause of death during myocardial infarction
Ventricular fibrillation
Damage to the AV node results in:
Heart Block